Search

Electrochemiluminescence (ECL) has been considered to have better performance in rapid detection. A novel paper-based ECL biosensing platform for hepatitis B surface antigen (HBsAg) detection was developed based on a simple paper discs, the flexible design of a machine and a circuit of the custom-made ECL device. Through the modified magnetic suspension sandwich immunoassay protocol, rapid and sensitive clinical HBsAg detection was realized on the developed platform. The platform was characterized using cyclic voltammetry (CV) and ECL methods and obtained a linear range of 34.2 pg/mL–34.2 ng/mL with a 34.2 pg/mL (3σ) detection limit. This paper-based ECL sandwich immunoassay showed high sensitivity and selectivity, acceptable reproducibility, fast analysis time and better performance than chemiluminescent immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) for detecting HBsAg in real clinical serum samples.

Paper mill sludge (PMS), a lignocellulosic waste from paper industry, is an ecological burden of environmental concern. Present study explored PMS as substrate for prodigiosin production in solid state fermentation (SSF) and concurrent source of cellulose for Cellulose nanocrystals (CNCs) preparation, using Serratia marcescens NITDPER1. Batch studies revealed maximum pigment production 47 ± 3.2 mg/L after 60 h and ligninolytic potentials via kraft lignin degradation (59 % after 72 h), lignin-mimicking dye decolourization and lignin monomer utilization. In SSF, highest yield was 30.05 ± 1.7 mg/g (24 h) with growth-associated (α = 20.84) and non-growth associated (β = 0.63) parameters determined through Luedeking-Piret model. Lambda max (535 nm), Thin-Layer Chromatography (TLC) (Rf = 0.9), High-Performance Liquid Chromatography (HPLC) (RT = 2.865), Fourier-transform infrared spectra (FT-IR) and Nuclear magnetic resonance (NMR) confirmed it as prodigiosin that exhibited antioxidant potential (IC50 = 47 ± 3.5 μg/mL). After SSF, the delignified (54 %) residual PMS was utilized for preparing CNCs, that displayed particle size 130.8 nm, zeta potential -13.4 mv, polydispersity index 0.404, stability upto 490 °C and revealed desirable properties in Field-emission scanning electron microscopy (FESEM), FT-IR and X-ray diffraction (XRD). Phytotoxicity studies confirmed both prodigiosin and CNCs as non-toxic. This study unveiled biorefinery perspectives for paper industries through production of two commercially important commodities from waste using eco-friendly approach.

A novel, portable, and disposable paper-based microbial fuel cells (MFC) generating electricity from harmless strain of Escherichia coli (E. coli) has been developed. This MFC is on-demand electricity generation activated by a drop of tap water in a dry anode containing the biofilm of E. coli. A low-cost, simple-structure MFC case was created by a single layer of paper filter with high order of folding, which could support interchangeable dry bacteria-loaded anodes. The paper filter was innovatively engineered to make an integrated air-cathode proton exchange membrane (ACPEM) by coating carbon nanotube mixed with potassium ferricyanide on one surface and spraying hydrophobic solution on the other surface, respectively. The E. coli biofilm pre-inoculated in the anodes made of activated carbon sheet was simply dried in the air for the sake of long-term storage and usage. The dry anodes can be simply set in the MFC case with the readily prepared ACPEM, which can be used for on-demand power generation within seconds after adding water with maximum power density of 8.8μW/cm2.

This study deals with the decolourisation and detoxification of rayon grade pulp paper mill effluent by mixed culture of three bacterial strains having ligninolytic enzyme activity. These strains were identified as IITRP1 Pseudochrobactrum glaciale (FJ581024), IITRP2 Providencia rettgeri (GU193984) and RCT2 Pantoea sp. (FJ755943) based on 16S rRNA gene sequencing. The results showed that mixed culture effectively reduced colour 96.02%, chemical oxygen demand (COD) 91% and biological oxygen demand (BOD) 92.59% of the pulp paper mill effluent within 216 h of the incubation period. Maximum enzyme activity for lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase were recorded at 48, 72 and 144 h of the incubation period, respectively. The high performance liquid chromatography (HPLC) analysis of bacterial degraded samples showed 90% reduction of lignin and chlorophenol compared to the untreated sample. Further, gas chromatography–mass spectroscopy (GC–MS) analysis revealed that majority of the compounds present in the untreated sample were completely removed and only few metabolites were generated after bacterial treatment. The toxicity assessment of the pulp paper mill effluent on Vicia faba L. showed 40% reduction after bacterial treatment. However, untreated effluent sample showed inhibition of seed germination and α-amylase activity.

To convert bleached softwood paper grade pulp into dissolving pulp for viscose application, two stages of treatments consisting of enzymatic treatment and alkaline peroxide treatment were investigated. It was found that high reactivity (about 80%) of pulp could be achieved by endoglucanases (EG)-rich industrial cellulase treatment, and the alpha-cellulose content as well as the viscosity of enzymatically treated pulp can be further adjusted by the alkaline peroxide treatment with certain dosages of NaOH and H2O2 to finally meet the quality requirements of dissolving pulp. The resulting pulp with 68.7% of reactivity, 92.1% of alpha-cellulose content, and 506.9 mL/g of pulp viscosity could be obtained after the two stages of treatments. The appropriate dosage of EG-rich cellulase was 300 IU/g bone dry pulp in the stage of enzymatic treatment, while the suitable dosages of NaOH and H2O2 were 9 wt% and 1 wt%, respectively, in the stage of alkaline peroxide treatment. (C) 2013 Elsevier B.V. All rights reserved.

We first reported a novel visualized instrument-free signal conversion method on paper for cardiovascular biomarker detection based on the coffee-ring effect (CRE). Our strategy was based on the principle that cTnI was captured by DNA probe decorated detection antibody to form sandwich complex, which could hybridize with H1 probes to form G-quadruplex DNAzyme. As a peroxidase mimic, G-quadruplex DNAzyme could catalyze colorimetric reaction and generate colored products, which were converted to the end edge of the paper by evaporation-driven flow, forming a visible colored band. Hence, the resulted colored signals were converted to distance signal by CRE, so that the quantification of cTnI could be measured easily only by a ruler. Our results demonstrated that the length of the colored bands was proportional to the concentration of cTnI, with a limit of detection of 1.0 pg/mL. Furthermore, this strategy not only showed advanced performance to discriminate cTnI from complex samples but also exhibited high accuracy with standard method in real sample. Hence, these results demonstrated that this method established a promising equipment-free and visualized platform for detecting various kinds of genetic diseases and biomarkers, further promoting the development of point-of-care testing (POCT) in biomedicine.

The hydrolytic kinetics of mixtures of cotton gin waste (CGW) and recycled paper sludge (RPS) at various initial enzyme concentrations of Spezyme™ AO3117 was investigated. The experiments showed that the concentrations of reducing sugars and the conversions of the mixtures increased with increasing initial enzyme concentration. The reducing sugar concentration and conversion of the mixture of 75% CGW and 25% RPS were higher than those of the mixture of 80% CGW and 20% RPS. The conversion of the former can reach 73.8% after a 72-h hydrolysis at the initial enzyme loading of 17.4 Filter Paper Unit (FPU)/g substrate. A three-parameter kinetic model based on enzyme deactivation and its analytical expression were derived. Using nonlinear regression, the parameters of the model were determined for the experimental data of hydrolytic kinetics of the mixtures. Based on this kinetic model of hydrolysis, two profit rate models, representing two kinds of operating modes with and without feedstock recycling, were developed. Using the profit rate models, the optimal enzyme loading and hydrolytic time can be predicted for the maximum profit rate in ethanol production according to the costs of enzyme and operation, enzyme loading, and ethanol market price. Simulated results from the models based on the experimental data of hydrolysis of the mixture of 75% CGW and 25% RPS showed that use of a high substrate concentration and an operating mode with feedstock recycle can greatly increase the profit rate in ethanol production. The results also demonstrated that the hydrolysis at a low enzyme loading is economically required for systematic optimization of ethanol production.

Three fungal strains were isolated from sediments of pulp and paper mill in which PF7 reduced colour (27%) and lignin content (24%) of the effluent on 5th day. PF7 was identified as Cryptococcus sp. isolate FIST3 on the basis of ITS1 and ITS2 region sequences. The process of decolourization optimized, in shake flask experiments, by Taguchi approach indicated optimum conditions: temperature (30–35 °C); shaking condition (125 rpm); dextrose (1.0% w/v); tryptone (0.1% w/v); inoculum size (7.5% w/v); pH (5) and duration (24 h). Overall evaluation criterion (OEC) value before optimization was 32.3. There was 38% improvement in the process with final OEC value, 44.6 ± 2.02, at optimum conditions. The colour content of the effluent reduced by 50–53% and lignin content 35–40% after treatment at optimum conditions. Variation in pH from 5 to 6 had most significant effect on decolourization (72%) while variation in temperature from 30 °C to 35 °C had no effect on the process. Treated effluent was further evaluated for toxicity by alkaline single cell (comet) gel electrophoresis (SCGE) assay using Saccharomyces cerevisiae MTCC 36 as model organism, indicated 45% reduction. The results showed significant reduction in colour, lignin and toxicity of the effluent and this process can be scale up to industrial level.

Filamentous foaming and bulking in activated sludge process are common problems in pulp and paper mill wastewater treatment processes. In this study, the predominant foaming and bulking causing filamentous microorganism in the pulp and paper mill effluent treatment system was identified. Its growth kinetics was studied and used as a theoretical basis to develop an optimal operational strategy for foaming and bulking preventive control. Filamentous actinomycetes, Nocardia amarae was found to be the predominant filamentous microorganisms. The kinetics study revealed that the Food to Microorganism (F/M) ratio was a critical factor affecting the excessive growth of N. amarae . Accordingly, a novel Feast-Fast Operation (FFO) strategy was developed, in which the sludge microbes underwent a repetitive switch between high and low F/M ratio during the course of wastewater treatment. Feast-to-Fast Loading Ratio (FFLR) was proposed and used as the parameter for optimization of FFO performance. At FFLR of 4 and 3.5, the sludge volume index (SVI) rapidly reduced to a healthy level of 70 ml g −1 and the systems were free from stable foam, while the biochemical oxygen demand (BOD) removal efficiency remained above 96.2%. The FFO strategy effectively suppressed filamentous overgrowth and improved the settleability of activated sludge without adversely affecting the BOD removal efficiency.

During past decades, the considerable efforts have been made to utilize lignocellulose as biomass feedstock for the optimal production of bio-ethanol as an alternative source of fuel. In this work, the effective bioconversion of paper sludge to ethanol was investigated by using Zymomonas mobilis NBRC 13756. Major components of the raw paper sludge were carbohydrates and ash. Fermentation utilizing strains of Z. mobilis instead of traditional yeasts and the use of simultaneous saccharification and fermentation (SSF) process have been proposed due to their high ethanol yields with cost-effectiveness. Free cells of Z. mobilis resulted in no ethanol production even after 24 h of incubation because cells’ growth was inhibited by metal ions contained in the paper sludge. The application of SSF with Ca-alginate-immobilized cells of Z. mobilis was performed and 18 g/L of ethanol was obtained after 48 h of incubation at an initial paper sludge concentration of 200 g/L. In addition, the repeated batch fermentation of Ca-alginate-immobilized Z. mobilis cells was attempted for producing ethanol up to run 4. Our work suggests that Ca-alginate-immobilized cells of Z. mobilis could effectively produce ethanol from paper sludge not only under the batch fermentation but also under the repeated batch fermentation.

Concentrated sludge generated in large amounts by the wastewater treatment facilities of recycling paper plants raises a serious disposal problem requiring urgent solution. This recycled paper sludge (RPS) is an industrial waste with high polysaccharide content. As previously demonstrated, cellulosic and hemicellulosic fractions of RPS can be completely converted by enzymatic hydrolysis (using Celluclast ® 1.5 L with Novozym ® 188) into the constitutive glucose and xylose. These monosaccharides can be used on fermentation media to obtain a variety of products, such as lactic acid, which has an expanding market as precursor of biodegradable polylactides. Hence the purpose of the present work is to evaluate the performance of RPS as feedstock for fermentative production of lactic acid (LA) with Lactobacillus rhamnosus ATCC 7469, a very efficient lactic acid bacterium. Maximum production of lactic acid from RPS was obtained by performing the hydrolysis and fermentation steps simultaneously on medium supplemented with MRS components and calcium carbonate. L. rhamnosus produced 73 g L −1 of lactic acid, corresponding to a maximum productivity of 2.9 g L −1 h −1 , with 0.97 g LA produced per g of carbohydrates on initial substrate. A process simplification was also implemented by minimizing RPS supplementation and suppressing Novozym cellobiase addition.

Production of lactic acid from recycled paper sludge by simultaneous saccharification and fermentation (SSF) has previously been implemented under a pulsed fed-batch mode. However, lactic acid concentrations above 58 g L−1 inhibit cultivation of the Lactobacillus rhamnosus strain used. Thereby, the present work targeted process intensification by running it into a membrane-recycle bioreactor, providing product removal together with reuse of enzymes and bacterial cells. A shear-enhanced flat sheet cross-flow filtration system was built, working properly with the high-solids concentration suspension. Based on product inhibition and solids concentration constraints, a model was proposed for operation of the membrane-recycle bioreactor. SSF should be run in batch mode into the fermentor for 48 h, and then switch-on recirculation through the filtration module, with pulsed fed-batch addition of recycled paper sludge. This innovative approach can be applied to improve other SSF processes dealing with high-solids concentrations, towards cost-effective lignocellulosic feedstock biorefineries.

Laboratory scale research on the effects of operating parameters, including mixed liquor suspended solid (MLSS) concentration, volumetric exchange rate (VER), aeration time, temperature and daily operation cycle on biological treatment of the pulp and paper mill effluent was studied using four 4 l sequencing batch reactors (SBR). The results revealed that chemical oxygen demand (COD) removal efficiency was up to 93.1 ± 0.3% and the volumetric loading reached 1.9 kg BOD m−3 day−1 under optimal operating conditions. The treatment performance of organic removal by the SBR system remained stable during the operation. The effluent quality was satisfied with the discharge standard set by the local authority and the filamentous bulking problem was solved. At the same time, the sludge settleability, in terms of sludge volume index (SVI), was improved to the healthy level (SVI = 52.7 ± 1.3 ml g−1).

Paper-based diagnostics are rapid, robust, affordable and user-friendly, thus have potential for point-of-care. Modulation of sample flow in these technologies have the advantage of increased exposure between immunoreagents, which ensures higher sensitivity and specificity. In this study, common membrane types were compared and modified to modulate sample flow. Five different membranes were compared: glassfiber, polyester, nitrocellulose, polyvinylidene-difluoride and cellulose. Several parameters were tested for their effect on the sample flow: membranes absorption capacity, immobilization of buffer solution, different membrane types as separation layer and sample volume. The effect of separation membrane on the sample flow was tested using a ‘Stack-Pad’ sensor layout. Higher antibody levels could reach the three absorption pads, with the use of polyester separation membrane (340, 440 and 408 RLU), as compared to the glassfiber separation membrane (208, 198 and 107 RLU), thus potentially increasing the sensor sensitivity. Lastly, the effect of the membrane type and its modifications on the detection sensitivity was also compared. The finalized modified setup (862 RLU) demonstrated a higher detection sensitivity vs. the initial setup (290 RLU). To conclude, the selection of membrane types and their modifications can modulate sample flow and increase the sensitivity of detection in paper diagnostics.

Lactic acid promises to be an important commodity chemical in the future as a monomer for the production of biodegradable polylactic acid. With the increase of the lactic acid demand, the need to explore alternative feedstock sources and purification processes that are inexpensive and efficient is becoming more important. This paper first reports the purification results of lactic acid from the fermentation broth with paper sludge as a cellulosic feedstock using weak anion exchanger Amberlite IRA-92. Some factors such as flow rate, sample volume loaded, pH, and column were systematically examined to improve the purity, yield and productivity in lactic acid purification. Adsorption isotherm of standard lactic acid and lactic acid in the fermentation broth by anion exchanger IRA-92 were also investigated. Results indicate that in purification process the increase of pH of the fermentation broth ranging from 5.0 to 6.0 can significantly enhance the recovery yield, purity and productivity. The decrease of flow rate and sample volume loaded can also improve the recovery yield and purity but apparently reduce the productivity. In addition, the scale-up of purification process in laboratory size has little influence on the recovery yield and purity. After optimization, the yield, purity and productivity are found to be about 82.6%, 96.2% and 1.16 g LA/(g-resin day), respectively.

Biomass wastes from oil palm production have the potential to be converted into high value bioproducts. Oil palm biomass (OPB) includes empty fruit bunch, mesocarp fibre, palm shell kernel, oil palm fronds and trunks. The production of microbial oils from OPB can be achieved through biochemical routes comprising pretreatment and enzymatic hydrolysis of OPB to produce fermentable sugars (OPB hydrolysates), followed by the cultivation of oleaginous microorganism on OPB hydrolysates. This paper reviews the methods and processes of producing microbial oils and biodiesel from OPB. This paper also presents conceptual microbial oil-based lignocellulosic biorefinery development within the palm oil industry, based on existing and not-yet-explored potential application of microbial oils. OPB-derived microbial oils are a promising non-food feedstock for the production of biodiesel and palm oil substitutes. Biorefining of OPB to microbial oils can be integrated with traditional palm oil processing operations to expand markets for food and oleochemicals. This integrated biorefinery has the potential to generate sustainable outcomes for the palm oil industry.